Added initial implementation of mocks for chrome StorageArea, adding first tests for storage helper

tests/mocks/ChromeEvent.ts

@@ -0,0 +1,9 @@
+export default class ChromeEvent<T extends Function> implements chrome.events.Event<T> {
+    addListener = vi.fn();
+    getRules = vi.fn();
+    hasListener = vi.fn();
+    removeRules = vi.fn();
+    addRules = vi.fn();
+    removeListener = vi.fn();
+    hasListeners = vi.fn();
+}

tests/mocks/ChromeLocalStorageArea.ts

@@ -0,0 +1,5 @@
+import ChromeStorageArea from "$tests/mocks/ChromeStorageArea";
+
+export class ChromeLocalStorageArea extends ChromeStorageArea implements chrome.storage.LocalStorageArea {
+    QUOTA_BYTES = 100000;
+}

tests/mocks/ChromeStorageArea.ts

@@ -0,0 +1,71 @@
+import ChromeEvent from "./ChromeEvent";
+
+type ChangedEventCallback = (changes: chrome.storage.StorageChange) => void
+
+export default class ChromeStorageArea implements chrome.storage.StorageArea {
+  #mockedData: Record<string, any> = {};
+
+  getBytesInUse = vi.fn();
+  clear = vi.fn((): Promise<void> => {
+    return new Promise(resolve => {
+      this.#mockedData = {};
+      resolve();
+    })
+  });
+  set = vi.fn((...args: any[]): Promise<void> => {
+    return new Promise((resolve, reject) => {
+      this.#mockedData = Object.assign(this.#mockedData, args[0]);
+      resolve();
+    })
+  });
+  remove = vi.fn((...args: any[]): Promise<void> => {
+    return new Promise((resolve, reject) => {
+      const key = args[0];
+
+      if (typeof key === 'string') {
+        delete this.#mockedData[key];
+        resolve();
+      }
+
+      reject(new Error('This behavior is not mocked!'));
+    });
+  });
+  get = vi.fn((...args: any[]) => {
+    return new Promise((resolve, reject) => {
+      const key = args[0];
+
+      if (!key) {
+        resolve(this.#mockedData);
+        return;
+      }
+
+      if (typeof key === 'string') {
+        resolve({[key]: this.#mockedData[key]});
+        return;
+      }
+
+      if (Array.isArray(key)) {
+        resolve(
+          (key as string[]).reduce((entries, key) => {
+            entries[key] = this.#mockedData[key];
+            return entries;
+          }, {} as Record<string, any>)
+        );
+        return;
+      }
+
+      reject(new Error('This behavior is not implemented by the mock.'));
+    });
+  });
+  setAccessLevel = vi.fn();
+  onChanged = new ChromeEvent<ChangedEventCallback>();
+  getKeys = vi.fn();
+
+  insertMockedData(data: Record<string, any>) {
+    this.#mockedData = data;
+  }
+
+  get mockedData(): Record<string, any> {
+    return this.#mockedData;
+  }
+}